Tunable metallic-like transport in polypyrrole

Conjugated polymers (CPs), organic macromolecules with a linear backbone of alternating C-C and C=C bonds, possess unique semiconductive properties, providing new opportunities for organic electronics, photonics, information, and energy devices. Seeking the metallic or metallic-like, even superconducting properties beyond semiconductivity in CPs is always one of the ultimate goals in polymer science and condensed matter. Only two metallic and semi-metallic transport cases-aniline-derived polyaniline and thiophene-derived poly(3,4-ethylenedioxythiophene)-have been reported since the development of CPs for four decades. Controllable synthesis is a key challenge in discovering more cases. Here we report the metallic-like transport behavior of another CP, polypyrrole (PPy). We observe that the transport behavior of PPy changes from semiconductor to insulator-metal transition, and gradually realizes metallic-like performance when the crystalline degree increases. Using a generalized Einstein relation model, we rationalized the mechanism behind the observation. The metallic-like transport in PPy demonstrates electron strong correlation and phonon-electron interaction in soft condensation matter, and may find practical applications of CPs in electrics and spintronics.

Automated summary

Conjugated polymers (CPs) with unique semiconductive properties have been explored for metallic or metallic-like properties, with only a few cases reported so far. Through controllable synthesis, researchers discovered metallic-like transport behavior in another CP, polypyrrole (PPy), demonstrating potential applications in electronics and spintronics.